The LCD (Liquid Crystal Display) possesses advantages of thin body, power saving, no radiation, to be widely used such as: LCD TVs, mobile phones, personal digital assistant (PDA), digital camera, computer screen or laptop screen, occupies the leading position in the flat panel display area.
The TFT-LCD (Thin Film Transistor Liquid Crystal Display) is one of the major types of flat panel display, the thin-film transistor liquid crystal display control picture display in advance with thin-film transistor switches control how data signal is entered.
Specifically, see FIG. 1, primary driving principle for TFT-LCD is, system board (not shown) is connected to the connector 100 on PCB 200 (Printed Circuit Board) by cable. Data such as R/G/B compressed signal and control signal and driving signal, will be processed by timing controller (TCON) in printed circuit board 200. The data goes to display area 500 through the source terminal (Source-Chip on Film, S-COF) 300 and gate terminals (Gate-Chip on Film, G-COF) 400, then provide required signals for LCD to display on screen.
Electrostatic discharge (ESD) is charge transfer induced by objects with different electrostatic potential getting close to each other or direct contacted. Electrostatic damage happened when electrostatic discharge instantaneously generates thousands of volts which will cause TFT-LCD malfunction. To prevent electrostatic damage, PCB ground is required for ESD protection.
In traditional design, working procedure is complicated while mounting PCB on back plate by screws or buckles, then poor contact between PCB and back plate easily happened because the contact of screws or buckles is uncontrollable, thus PCB grounding quality is not guaranteed. While interferences like electrostatic discharge transferred to PCB from environment, it cannot be conduct promptly to the back plate then bad ESD happened. To resolve this problem, additional fixing mechanisms are required for traditional design to increase grounding quality, and the production cost also rises.